Device and method for continuously removing impurities from molten metal

ABSTRACT

A device for continuously removing impurities from molten metal includes a molten metal flow path body, an inlet-side closed end plate and an outlet-side closed end plate are provided in the molten metal flow path body so as to form an impurity removal space, an electrode device composed of an inlet-side electrode and an outlet-side electrode that face each other in a longitudinal direction of the molten metal flow path body, a magnetic field device composed of a pair of permanent magnets that face each other in a width direction, sandwich the impurity removal space, and an urging device composed of the electrode device and the magnetic field device applies a Lorentz force downward to molten metal in the impurity removal space so as to increase a density of the molten metal and cause impurities in the molten metal to rise up to a surface of the molten metal.

TECHNICAL FIELD

The present invention relates to a device and a method for continuouslyremoving impurities from molten metal.

BACKGROUND ART

Conventionally, productization from molten metal having electricalconductivity (conductivity), that is, non-ferrous molten metal (e.g.,Al, Cu, Zn, or Si, alloy including at least two of these, Mg alloy, orthe like) or molten metal other than non-ferrous molten metal includes,for example, steps of dissolving raw materials, adjusting components,removing impurities mixed in molten metal, and molding. Removal ofimpurities is generally referred to as purification of molten metal,and, for example, a ceramic filter is used therefor.

However, since an impurity removal method using a filter is, of course,a filtration method, clogging is likely to occur. Therefore, there is aproblem such that the workability is deteriorated and the running costis increased.

In other words, in a case of a filter type, how large the mesh is set tois actually an important point. In order to remove not only largeimpurities but also fine impurities, the mesh must be fine. However, ifthe mesh is made fine, clogging is more likely to occur. For example,clogging may occur instantaneously, and production may stop.

Thus, conventionally, flux is previously introduced into the moltenmetal prior to removal with a filter. By such introduction, impuritiesare changed into substances having a large particle size. As a result,it becomes possible to remove impurities while keeping the mesh large tosome extent, and it is possible to increase the removal efficiency (trapefficiency) of the filter. However, it is not preferable to introduceflux into the molten metal in terms of product quality in many cases.

SUMMARY OF INVENTION Technical Problem

As described above, according to a conventional method, it is actuallyimpossible to continuously produce products without stopping productionof products while removing impurities, including fine impurities, frommolten metal.

The present invention has been made in view of such circumstances, andit is an object thereof to provide a device and a method forcontinuously removing impurities for enabling continuous manufacture ofproducts while removing impurities from non-ferrous metal or othermolten metal containing impurities with high accuracy.

Solution to Problem

An embodiment of the present invention is

a device for continuously removing impurities from molten metal, whichsends electrically conductive molten metal to a metal productmanufacturing device in a next stage, the device including:

a molten metal flow path body having a molten metal flow path forflowing electrically conductive molten metal that has flown from outsidetoward the metal product manufacturing device;

an inlet-side closed end plate and an outlet-side closed end plate thatare provided in the molten metal flow path body so as to partition afront and a rear of the molten metal flow path and form an impurityremoval space;

an electrode device composed of an inlet-side electrode and anoutlet-side electrode that are provided in the impurity removal space,face each other in a longitudinal direction in which molten metal flows,and can be put into electrical contact with molten metal in the impurityremoval space; and

a magnetic field device composed of a pair of permanent magnets that areprovided outside the molten metal flow path forming body, face eachother in a width direction intersecting the longitudinal direction,sandwich the impurity removal space of the molten metal flow pathforming body in the width direction, have opposite poles facing eachother, and can form a magnetic field in molten metal in the impurityremoval space,

in which the electrode device and the magnetic field device constitutean urging device that can apply a Lorentz force downward to molten metalin the impurity removal space so as to increase a density of the moltenmetal and cause impurities in the molten metal to rise up to a surfaceof the molten metal.

Furthermore, an embodiment of the present invention is

a continuous impurity removal method for removing impurities from moltenmetal in sending electrically conductive molten metal to a metal productmanufacturing device in a next stage, the method including:

preparing a molten metal flow path body having a molten metal flow pathfor flowing electrically conductive molten metal that has flown fromoutside toward the metal product manufacturing device;

providing an inlet-side closed end plate and an outlet-side closed endplate in the molten metal flow path body so as to partition a front anda rear of the molten metal flow path and form an impurity removal space;

providing, in the impurity removal space, an electrode device composedof an inlet-side electrode and an outlet-side electrode that face eachother in a longitudinal direction in which molten metal flows and can beput into electrical contact with molten metal in the impurity removalspace;

providing, outside the molten metal flow path forming body, a magneticfield device composed of a pair of permanent magnets that face eachother in a width direction intersecting the longitudinal direction,sandwich the impurity removal space of the molten metal flow pathforming body in the width direction, have opposite poles facing eachother, and can form a magnetic field in molten metal in the impurityremoval space; and

causing an urging device composed of the electrode device and themagnetic field device to apply a Lorentz force downward to molten metalin the impurity removal space so as to increase a density of the moltenmetal and cause impurities in the molten metal to rise up to a surfaceof the molten metal.

Furthermore, an embodiment of the present invention is

a device for continuously removing impurities from molten metal, whichsends electrically conductive molten metal to a metal productmanufacturing device in a next stage, the device including:

a molten metal flow path body having a molten metal flow path forflowing electrically conductive molten metal that has flown from outsidetoward the metal product manufacturing device;

an inlet-side closed end plate and an outlet-side closed end plate thatare provided in the molten metal flow path body so as to partition afront and a rear of the molten metal flow path and form an impurityremoval space;

an electrode device composed of an inlet-side electrode and anoutlet-side electrode that are provided in the impurity removal space,face each other in a longitudinal direction in which molten metal flows,and can be put into electrical contact with molten metal in the impurityremoval space; and

a magnetic field device composed of a pair of permanent magnets that areprovided outside the molten metal flow path forming body, face eachother in a width direction intersecting the longitudinal direction,sandwich the impurity removal space of the molten metal flow pathforming body in the width direction, have opposite poles facing eachother, and can form a magnetic field in molten metal in the impurityremoval space,

in which the outlet-side electrode is provided in a floating state inthe impurity removal space so that a first gap opened vertically isformed between the outlet-side electrode and a bottom surface of themolten metal flow path forming body and a second gap opened in thelongitudinal direction is formed between the outlet-side electrode andthe outlet-side closed end plate, and

the electrode device and the magnetic field device constitute an urgingdevice that can apply a Lorentz force downward to molten metal in theimpurity removal space so as to increase a density of the molten metaland cause impurities in the molten metal to rise up to a surface of themolten metal, and can send molten metal on an inner side than theoutlet-side electrode in the impurity removal space through the firstgap to the second gap.

Furthermore, an embodiment of the present invention is

a continuous impurity removal method for removing impurities from moltenmetal in sending electrically conductive molten metal to a metal productmanufacturing device in a next stage, the method including:

preparing a molten metal flow path body having a molten metal flow pathfor flowing electrically conductive molten metal that has flown fromoutside toward the metal product manufacturing device;

providing an inlet-side closed end plate and an outlet-side closed endplate in the molten metal flow path body so as to partition a front anda rear of the molten metal flow path and form an impurity removal space;

providing, in the impurity removal space, an electrode device composedof an inlet-side electrode and an outlet-side electrode that face eachother in a longitudinal direction in which molten metal flows and can beput into electrical contact with molten metal in the impurity removalspace;

providing, outside the molten metal flow path forming body, a magneticfield device composed of a pair of permanent magnets that face eachother in a width direction intersecting the longitudinal direction,sandwich the impurity removal space of the molten metal flow pathforming body in the width direction, have opposite poles facing eachother, and can form a magnetic field in molten metal in the impurityremoval space;

providing the outlet-side electrode in a floating state in the impurityremoval space so that a first gap opened vertically is formed betweenthe outlet-side electrode and a bottom surface of the molten metal flowpath forming body and a second gap opened in the longitudinal directionis formed between the outlet-side electrode and the outlet-side closedend plate; and

causing an urging device composed of the electrode device and themagnetic field device to apply a Lorentz force downward to molten metalin the impurity removal space so as to increase a density of the moltenmetal and cause impurities in the molten metal to rise up to a surfaceof the molten metal, and send molten metal on an inner side than theoutlet-side electrode through the first gap to the second gap.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is an explanatory plan view illustrating the overallconfiguration of a device for continuously removing impurities frommolten metal according to an embodiment of the present invention.

FIG. 2 is an explanatory sectional view taken along line II-II of FIG.1.

FIG. 3 is an explanatory sectional view taken along line III-III of FIG.2.

FIG. 4 is an explanatory sectional view taken along line IV-IV of FIG.2.

FIG. 5 is an explanatory view illustrating a usage state correspondingto a part of FIG. 2.

FIG. 6 is an explanatory view for explaining generation of a Lorentzforce.

FIG. 7a is an explanatory view for explaining a pressure state in moltenmetal.

FIG. 7b is an explanatory view for explaining a pressure state in moltenmetal.

FIG. 8 is an explanatory partial view illustrating a modified examplecorresponding to FIG. 5.

FIG. 9a is an explanatory longitudinal sectional view illustrating aspecific example of an outlet-side closed end plate.

FIG. 9b is an explanatory longitudinal sectional view illustrating aspecific example of an outlet-side closed end plate.

DESCRIPTION OF EMBODIMENTS

Hereinafter, embodiments of the present invention will be described withreference to the drawings.

FIG. 1 is an explanatory plan view illustrating the entire configurationof an embodiment of a device 100 for continuously removing impuritiesfrom molten metal according to the present invention. The metal is anon-ferrous metal having electrical conductivity or another metal. Thenon-ferrous metal or another metal is a non-ferrous metal of a conductor(electric conductor) such as Al, Cu, Zn, an alloy including at least twoof these, or an Mg alloy, or a metal other than the non-ferrous metal.

In FIG. 1, the flow of molten metal M is indicated by a solid arrow AR1,and the movement of impurities IM is indicated by a broken arrow AR2.That is, it is shown that the impurities IM are removed laterally whilethe molten metal M is flowing along the arrow AR1.

More specifically, FIG. 1 illustrates a case where a tilting typemelting furnace is used as an example. As can be seen from FIG. 1, theimpurity removing device 100 receives molten metal M from a meltingfurnace 200 in the preceding stage, allows the molten metal M flowinside the impurity removing device 100, causes impurities in the moltenmetal M to positively rise up to the vicinity of the liquid surfaceduring the molten metal M is flowing so that the impurities can beremoved by arbitral means, and causes the molten metal M to flow into amold 300 in the following stage after impurities are removed, so that aproduct (ingot) such as a billet or a slab, for example, can bemanufactured from high-quality molten metal M. A general-purpose meltingfurnace 200 and a general-purpose mold 300 can be employed. Therefore,for example, the impurity removing device 100 of the present inventioncan be additionally provided to an existing melting furnace 200 and anexisting mold 300 later.

The melting furnace 200 is a general-purpose tilting type meltingfurnace as described above. That is, the melting furnace 200 includes acontainer-shaped melting furnace main body 1 having an opening 2 at thetop. A spout 3 for the molten metal M is formed at a side wall on thefront side (left side in the figure) of the tilting type melting furnacemain body 1. A general-purpose gas burner 4 is attached to a rear sidewall. The raw material of the electrically conductive metal introducedfrom the opening 2 is heated by the gas burner 4 to be molten metal Mand is housed in the melting furnace main body 1.

FIG. 2 is an explanatory longitudinal sectional view taken along lineII-II of FIG. 1. As can be seen from FIG. 2, a hinge mechanism 6 isprovided at an outer bottom portion of the melting furnace main body 1so as to be able to derrick and rotate. As a result, it is configured tobe able to derrick and rotate on a horizontal shaft 6 a from an uprightstate to an inclined pouring state. This melting furnace main body 1 canadjust the amount of molten metal supplied to a gutter main body 10. Themolten metal M is poured from the spout 3 to the impurity removingdevice 100 in the next stage by tilting the melting furnace main body 1.This state is illustrated in FIG. 5. By adjusting the angle at which themelting furnace main body 1 is inclined, the head h illustrated in FIG.2 is changed, and the flow rate of the molten metal M from the meltingfurnace main body 1 to the gutter main body 10 can be changed. It is tobe noted that the level of the molten metal M in the gutter main body 10is performed by changing the height of an outlet-side closed end plate11. Moreover, as illustrated in FIG. 8, one electrode 13 b, which willbe described later, can be provided separately from the inlet-sideclosed end plate 8. The flow of the molten metal M at this time is asillustrated in FIG. 8.

The impurity removing device 100 that receives the molten metal M fromthe melting furnace 200 is configured to have a function as a so-calledgutter that allows the received molten metal M flow from right to leftin FIG. 1 and give the molten metal M to the mold 300 in the next stage,and a selective accumulation function of selectively accumulatingimpurities in the molten metal M that are caused to rise up to thevicinity of the liquid surface during the flow.

That is, as can be seen particularly from FIG. 2, the impurity removingdevice 100 includes the gutter main body (sorting tank) (molten metalflow path body) 10, and a magnetic field device 12 that sandwiches thegutter main body 10 in the width direction. Furthermore, as can be seenparticularly from FIG. 1, the impurity removing device 100 has anelectrode device 13 composed of a pair of electrodes 13 a and 13 b thatare housed inside the gutter main body 10 (molten metal flow path) andface each other. The magnetic field device 12 and the electrode device13 constitute an urging device 30 that applies a Lorentz force fdownward to the molten metal M, as will be described later in detail.

As can be seen from FIG. 1, the gutter main body 10 is configured toguide the molten metal M from the melting furnace 200 to the mold 300,and the gutter main body 10 is made of a refractory material and has asubstantially U-shaped cross section as can be seen from FIG. 3. Thegutter main body 10 can be installed with a gradient so that the leftside becomes lower than the right side in FIG. 2 in order to make theflow of the molten metal M smooth.

As can be seen from FIG. 2, the gutter main body 10 has an inflowauxiliary plate 7A that receives the molten metal M from the meltingfurnace 200, and an inlet-side closed end plate 8, a main flow pathbottom plate 9, and the outlet-side closed end plate 11 that follow.Furthermore, there are right and left side plates 15 a and 15 bsandwiching these members in the width direction. The right and leftside plates 15 a and 15 b, the inlet-side closed end plate 8, and theoutlet-side closed end plate 11 form a main flow path (impurity removalspace) 14 as an impurity removal portion.

The outlet-side closed end plate 11 can be configured such that theheight thereof can be adjusted. Arbitral configuration configured suchthat the height thereof can be adjusted can be employed. For example, ascan be seen from FIGS. 9a and 9b , the outlet-side closed end plate 11may be composed of a main body 11 a and an auxiliary plate 11 b whichare bolted to each other, and the auxiliary plate 11 b may be verticallyshifted with respect to the main body 11 a.

The inlet-side electrode 13 a in the electrode device 13 is provided inclose contact with the inlet-side closed end plate 8, and theoutlet-side electrode 13 b is spaced from the outlet-side closed endplate 11 with a gap (second gap) G2 in the longitudinal direction and isprovided in a floating state of floating with a gap (first gap) G1 inthe depth direction. As a result, the molten metal M flows through thegaps G1 and G2, flows over the outlet-side closed end plate 11, orso-called overflows, and flows out from the main flow path 8 through anoutflow auxiliary plate 7B toward the mold 300 as will be describedlater.

A power supply 16 is connected between the pair of electrodes 13 a and13 b in the electrode device 13. This power supply 16 is configured tobe able to pass an alternating current as well as a direct current.Furthermore, it is configured to switch the polarity of a directcurrent.

The magnetic field device 12 is provided on both right and left sides ofthe gutter main body 10 as can be seen from FIGS. 1 and 4. This magneticfield device 12 includes a pair of right and left permanent magnets 12 aand 12 b, and the gutter main body 10 is sandwiched between the pair ofpermanent magnets 12 a and 12 b. The pair of permanent magnets 12 a and12 b have opposite poles facing each other, and in this embodiment, theinner sides of the pair of permanent magnets 12 a and 12 b aremagnetized respectively to an S pole and an N pole. As a result, thelines of magnetic force ML from an upper permanent magnet 12 b in FIG. 4penetrate the molten metal M in the gutter main body 10 and reach alower permanent magnet 12 a. Thus, in actual use, a current I flowsbetween the pair of electrodes 13 a and 13 b as can be seen from FIG. 4.Therefore, the lines of magnetic force ML and the current I intersecteach other. As a result, a Lorentz force f to push the molten metal Mdownward is generated in the molten metal M as illustrated in FIG. 6. Itis to be noted that the magnetic field device 12 can be constituted ofan electromagnet.

Next, the operation of the embodiment of the present invention will bedescribed.

As can be seen from FIGS. 1 and 2, when electrically conductive metal isintroduced into the melting furnace 200 and is heated and molten, themolten metal M is caused to flow from the melting furnace 200 into themain flow path 14 by increase of the molten metal M and the tiltillustrated in FIG. 5.

In this main flow path 14, the lines of magnetic force ML and thecurrent I intersect each other as can be seen from FIG. 4. This conceptis illustrated in FIG. 6 described above. As a result, a Lorentz force fis generated and acts on the molten metal M as a force in a direction topush the molten metal M downward. As a result, the pressure inside themolten metal M increases as it goes from the surface to a bottomportion. The state of pressure distribution in this case is illustratedin FIG. 7a . That is, the density of the molten metal M becomes largertoward the bottom portion due to the gravity in addition to the Lorentzforce f. This density affects greatly the buoyancy of impurities IMcontained in the molten metal M. That is, when the density is high, alarge buoyancy acts on impurities IM.

Therefore, in a state in which the Lorentz force f is generated,impurities IM in the molten metal M rise in the molten metal M and reachthe liquid level. That is, impurities IM tend to settle in the moltenmetal M by its own weight. Moreover, a buoyancy due to the molten metalM acts on impurities IM. Thus, when the density of the molten metal Mincreases, a large buoyancy acts on impurities IM in the molten metal M.Therefore, impurities IM rise or fall according to a difference betweenthe buoyancy and the settlement force. Thus, by setting the Lorentzforce f to an expected value, the buoyancy becomes larger than thesettlement force, and impurities IM rise in the molten metal M and reachthe vicinity of the liquid surface. This operation is continuouslyperformed in the process of flow of the molten metal M through the mainflow path 14.

In this way, impurities IM rise up to the vicinity of the surface of themolten metal M. Impurities IM that have risen up are automatically orartificially discharged to an impurity receiver 40 via the impurityremoving plate 7C as can be seen from FIG. 3 by arbitral means. Asillustrated in FIG. 3, the impurity removing plate 7C has amountain-shaped cross section.

Moreover, in the gutter main body 10, the molten metal M is pushed downby application of pressure as illustrated in FIG. 7b as described aboveto decrease the liquid level. Along with this, the molten metal M flowsthrough the gap G1 and reaches the gap G2 as can be seen from FIG. 2. Asa result, a head h is generated, and a pressure corresponding to thehead h is applied to the molten metal M in the gutter main body 10 asillustrated in FIG. 2. Here, since impurities IM rise in the moltenmetal M and gather in the vicinity of the liquid surface, the moltenmetal M flowing through the gap G1 contains substantially no impurityIM. That is, molten metal M substantially containing no impurity IMexists in the gap G2. Thus, the liquid level of the molten metal M risesin the gap G2. Therefore, the substantially purified molten metal Mflows over the outlet-side closed end plate 11 and flows into the mold30 via the outflow auxiliary plate 7B. As a result, a high-qualityproduct with less impurities IM can be obtained. In FIG. 2, h denotes ahead of two liquid levels.

The above-described fact that application of the Lorentz force f cancause impurities IM in the molten metal M to rise in the molten metal Mwill be described below in detail.

The magnetic field strength in the molten metal M in FIG. 4 will bedenoted by B. Here, as can be seen from FIGS. 7a and 7b , it is assumedthat a Lorentz force f is generated downward. At this time, a force Fthat acts on a bottom portion of the gutter main body 10 is the sum of aforce fg due to the gravity and a force fm due to the Lorentz force f,and is expressed as the following expression.

F=fg+fm

Here, since the horizontal area A of the gutter main body 10 is A=l×a(l: the length of the gutter main body 10, a: the width of the guttermain body 10), the pressure P at a bottom portion of the gutter mainbody 10 is expressed as the following expression.

P=F/A Furthermore, assuming here that the current density between thepair of electrodes 13 a and 13 b is constant, the Lorentz force fbecomes zero at the surface of the molten metal, and I×B×l (N) at abottom portion. Thus, the pressure is highest at a bottom portion. Thisstate is illustrated in FIGS. 7a and 7 b.

Furthermore, the apparent density of the molten metal M affected by twoinfluences of the Lorentz force f and the gravity is denoted by ρm, thedensity of mixed impurity particles is denoted by ρs, and the particlesize is denoted by V. The buoyancy fa received from the molten metal Mand the force fg due to the gravity simultaneously act on the impurityparticles. At this time, assuming that the force received by theimpurity particles is denoted by Fs, the following expression issatisfied.

$\begin{matrix}{{Fs} = {{fa} - {fg}}} \\{= {{\rho \; m \times V} - {\rho \; s \times V}}} \\{= {\left( {{\rho \; m} - {\rho \; s}} \right) \times V}}\end{matrix}$

Accordingly, the impurity particles move in the molten metal M asfollows.

(a) ρm−ρs>0 Rise

(b) ρm−ρs<0 Settlement

(c) ρm−ρs=0 Floating

With the embodiment of the present invention described above, thefollowing advantages can be obtained.

(1) Continuous purification of molten metal M is possible, which isconsistent with a continuous casting method that has become a standardtechnology in the industry.

(2) Although the rise speed of impurities varies depending on theparticle size, density, and the like of impurities, the residence timeof the molten metal M in the gutter main body (sorting tank) may beincreased by slowing down the flow speed or lengthening the gutter mainbody, for example, in the case of separating objects (having smallparticle size) having a low rise speed.

(3) Since the purification is neither physical nor mechanical, there isno need to replace a filter, which not only improves the work efficiencybut also reduces costs.

(4) The specific gravity of the molten metal can be easily changed bychanging the magnetic field strength or the current value, and animpurity removing operation can be performed according to the type ofthe molten metal M to be subjected to impurity removal.

1. A device for continuously removing impurities from molten metal,which sends electrically conductive molten metal to a metal productmanufacturing device in a next stage, the device comprising: a moltenmetal flow path body having a molten metal flow path for flowingelectrically conductive molten metal that has flown from outside towardthe metal product manufacturing device; an inlet-side closed end plateand an outlet-side closed end plate that are provided in the moltenmetal flow path body so as to partition a front and a rear of the moltenmetal flow path and form an impurity removal space; an electrode devicecomposed of an inlet-side electrode and an outlet-side electrode thatare provided in the impurity removal space, face each other in alongitudinal direction in which molten metal flows, and can be put intoelectrical contact with molten metal in the impurity removal space; anda magnetic field device composed of a pair of permanent magnets that areprovided outside the molten metal flow path forming body, face eachother in a width direction intersecting the longitudinal direction,sandwich the impurity removal space of the molten metal flow pathforming body in the width direction, have opposite poles facing eachother, and can form a magnetic field in molten metal in the impurityremoval space, wherein the electrode device and the magnetic fielddevice constitute an urging device that can apply a Lorentz forcedownward to molten metal in the impurity removal space so as to increasea density of the molten metal and cause impurities in the molten metalto rise up to a surface of the molten metal.
 2. The device forcontinuously removing impurities from molten metal according to claim 1,wherein a power supply that can adjust an amount of current so as toadjust the Lorentz force is connected with the pair of electrodes in theelectrode device.
 3. The device for continuously removing impuritiesfrom molten metal according to claim 1, wherein the outlet-side closedend plate is configured to be capable of adjusting a mounting positionin the molten metal flow path body in the longitudinal direction so asto adjust a length of the impurity removal space.
 4. The device forcontinuously removing impurities from molten metal according to claim 1,wherein the outlet-side electrode is provided in a floating state in theimpurity removal space so that a first gap opened vertically is formedbetween the outlet-side electrode and a bottom surface of the moltenmetal flow path forming body and a second gap opened in the longitudinaldirection is formed between the outlet-side electrode and theoutlet-side closed end plate.
 5. The device for continuously removingimpurities from molten metal according to claim 1, wherein theoutlet-side closed end plate is configured such that a height of theoutlet-side closed end plate can be adjusted so that an amount of moltenmetal that overflows can be adjusted.
 6. The device for continuouslyremoving impurities from molten metal according to claim 1, wherein amolten metal supply device that supplies molten metal to the moltenmetal flow path body and can adjust a supply amount is provided in apreceding stage of the molten metal flow path body.
 7. A continuousimpurity removal method for removing impurities from molten metal insending electrically conductive molten metal to a metal productmanufacturing device in a next stage, the method comprising: preparing amolten metal flow path body having a molten metal flow path for flowingelectrically conductive molten metal that has flown from outside towardthe metal product manufacturing device; providing an inlet-side closedend plate and an outlet-side closed end plate in the molten metal flowpath body so as to partition a front and a rear of the molten metal flowpath and form an impurity removal space; providing, in the impurityremoval space, an electrode device composed of an inlet-side electrodeand an outlet-side electrode that face each other in a longitudinaldirection in which molten metal flows and can be put into electricalcontact with molten metal in the impurity removal space; providing,outside the molten metal flow path forming body, a magnetic field devicecomposed of a pair of permanent magnets that face each other in a widthdirection intersecting the longitudinal direction, sandwich the impurityremoval space of the molten metal flow path forming body in the widthdirection, have opposite poles facing each other, and can form amagnetic field in molten metal in the impurity removal space; andcausing an urging device composed of the electrode device and themagnetic field device to apply a Lorentz force downward to molten metalin the impurity removal space so as to increase a density of the moltenmetal and cause impurities in the molten metal to rise up to a surfaceof the molten metal.
 8. The method for continuously removing impuritiesfrom molten metal according to claim 7, further comprising adjusting anamount of current applied from a power supply to the pair of electrodesin the electrode device so as to adjust the Lorentz force.
 9. The methodfor continuously removing impurities from molten metal according toclaim 7, further comprising a step of adjusting a mounting position ofthe outlet-side closed end plate in the molten metal flow path body inthe longitudinal direction so as to adjust a length of the impurityremoval space.
 10. The method for continuously removing impurities frommolten metal according to claim 7, wherein the outlet-side electrode isprovided in a floating state in the impurity removal space so that afirst gap opened vertically is formed between the outlet-side electrodeand a bottom surface of the molten metal flow path forming body and asecond gap opened in the longitudinal direction is formed between theoutlet-side electrode and the outlet-side closed end plate.
 11. Themethod for continuously removing impurities from molten metal accordingto claim 7, wherein the outlet-side closed end plate is configured suchthat a height of the outlet-side closed end plate can be adjusted and anamount of molten metal that overflows can be adjusted.
 12. The methodfor continuously removing impurities according to claim 7, wherein amolten metal supply device provided in a preceding stage of the moltenmetal flow path body adjusts an amount of molten metal supplied to themolten metal flow path body.
 13. A device for continuously removingimpurities from molten metal, which sends electrically conductive moltenmetal to a metal product manufacturing device in a next stage, thedevice comprising: a molten metal flow path body having a molten metalflow path for flowing electrically conductive molten metal that hasflown from outside toward the metal product manufacturing device; aninlet-side closed end plate and an outlet-side closed end plate that areprovided in the molten metal flow path body so as to partition a frontand a rear of the molten metal flow path and form an impurity removalspace; an electrode device composed of an inlet-side electrode and anoutlet-side electrode that are provided in the impurity removal space,face each other in a longitudinal direction in which molten metal flows,and can be put into electrical contact with molten metal in the impurityremoval space; and a magnetic field device composed of a pair ofpermanent magnets that are provided outside the molten metal flow pathforming body, face each other in a width direction intersecting thelongitudinal direction, sandwich the impurity removal space of themolten metal flow path forming body in the width direction, haveopposite poles facing each other, and can form a magnetic field inmolten metal in the impurity removal space, wherein the outlet-sideelectrode is provided in a floating state in the impurity removal spaceso that a first gap opened vertically is formed between the outlet-sideelectrode and a bottom surface of the molten metal flow path formingbody and a second gap opened in the longitudinal direction is formedbetween the outlet-side electrode and the outlet-side closed end plate,and the electrode device and the magnetic field device constitute anurging device that can apply a Lorentz force downward to molten metal inthe impurity removal space so as to increase a density of the moltenmetal and cause impurities in the molten metal to rise up to a surfaceof the molten metal, and can send molten metal on an inner side than theoutlet-side electrode in the impurity removal space through the firstgap to the second gap.
 14. A continuous impurity removal method forremoving impurities from molten metal in sending electrically conductivemolten metal to a metal product manufacturing device in a next stage,the method comprising: preparing a molten metal flow path body having amolten metal flow path for flowing electrically conductive molten metalthat has flown from outside toward the metal product manufacturingdevice; providing an inlet-side closed end plate and an outlet-sideclosed end plate in the molten metal flow path body so as to partition afront and a rear of the molten metal flow path and form an impurityremoval space; providing, in the impurity removal space, an electrodedevice composed of an inlet-side electrode and an outlet-side electrodethat face each other in a longitudinal direction in which molten metalflows and can be put into electrical contact with molten metal in theimpurity removal space; providing, outside the molten metal flow pathforming body, a magnetic field device composed of a pair of permanentmagnets that face each other in a width direction intersecting thelongitudinal direction, sandwich the impurity removal space of themolten metal flow path forming body in the width direction, haveopposite poles facing each other, and can form a magnetic field inmolten metal in the impurity removal space; providing the outlet-sideelectrode in a floating state in the impurity removal space so that afirst gap opened vertically is formed between the outlet-side electrodeand a bottom surface of the molten metal flow path forming body and asecond gap opened in the longitudinal direction is formed between theoutlet-side electrode and the outlet-side closed end plate; and causingan urging device composed of the electrode device and the magnetic fielddevice to apply a Lorentz force downward to molten metal in the impurityremoval space so as to increase a density of the molten metal and causeimpurities in the molten metal to rise up to a surface of the moltenmetal, and send molten metal on an inner side than the outlet-sideelectrode through the first gap to the second gap.